Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2016

Stock-Based Compensation

Schedule of stock-based compensation expense as reflected in the Company's condensed consolidated statements of operations and comprehensive loss

Stock-based compensation expense as reflected in the Company’s condensed consolidated statements of operations and comprehensive loss was as follows (in thousands):

	Three Months Ended March 31,
	2015		2016
Research and development	$	1,814	$	3,666
Selling, general and administrative		2,106		5,592
Total stock-based compensation expense	$	3,920	$	9,258

Summary of the Company's stock option activity and related information

		Weighted-average
		exercise price per
	Shares	share
Outstanding at December 31, 2015	5,878,352	$	35.00
Granted	1,298,421		43.22
Exercised	(29,689)		24.56
Cancelled	(79,531)		49.95
Outstanding at March 31, 2016	7,067,553	$	36.39
Vested at March 31, 2016	2,646,197	$	18.39
Vested and expected to vest at March 31, 2016 (a)	6,527,560	$	35.44

(a) This represents the number of vested options as of March 31, 2016, plus the number of unvested options expected to vest as of March 31, 2016, based on the unvested options at March 31, 2016, adjusted for the estimated forfeiture rate.

Summary of the Company's restricted stock unit (RSU) activity and related information

		Weighted-average
		grant date fair
	Shares	value per share
Unvested restricted stock units at December 31, 2015	60,000	$	56.00
Granted	480,995		43.31
Vested	—		—
Forfeited	(3,700)		43.39
Unvested restricted stock units at March 31, 2016	537,295	$	44.72